vp9_encodeframe.c

/*
 *  Copyright (c) 2010 The WebM project authors. All Rights Reserved.
 *
 *  Use of this source code is governed by a BSD-style license
 *  that can be found in the LICENSE file in the root of the source
 *  tree. An additional intellectual property rights grant can be found
 *  in the file PATENTS.  All contributing project authors may
 *  be found in the AUTHORS file in the root of the source tree.
 */


#include "vpx_ports/config.h"
#include "vp9/encoder/vp9_encodeframe.h"
#include "vp9/encoder/vp9_encodemb.h"
#include "vp9/encoder/vp9_encodemv.h"
#include "vp9/common/vp9_common.h"
#include "vp9/encoder/vp9_onyx_int.h"
#include "vp9/common/vp9_extend.h"
#include "vp9/common/vp9_entropy.h"
#include "vp9/common/vp9_entropymode.h"
#include "vp9/common/vp9_quant_common.h"
#include "vp9/encoder/vp9_segmentation.h"
#include "vp9/common/vp9_setupintrarecon.h"
#include "vp9/common/vp9_reconintra4x4.h"
#include "vp9/encoder/vp9_encodeintra.h"
#include "vp9/common/vp9_reconinter.h"
#include "vp9/common/vp9_invtrans.h"
#include "vp9/encoder/vp9_rdopt.h"
#include "vp9/common/vp9_findnearmv.h"
#include "vp9/common/vp9_reconintra.h"
#include "vp9/common/vp9_seg_common.h"
#include "vp9/encoder/vp9_tokenize.h"
#include "vp9_rtcd.h"
#include <stdio.h>
#include <math.h>
#include <limits.h>
#include "vpx_ports/vpx_timer.h"
#include "vp9/common/vp9_pred_common.h"
#include "vp9/common/vp9_mvref_common.h"

#define DBG_PRNT_SEGMAP 0

// #define ENC_DEBUG
#ifdef ENC_DEBUG
int enc_debug = 0;
#endif

extern void select_interp_filter_type(VP9_COMP *cpi);

static void encode_macroblock(VP9_COMP *cpi, MACROBLOCK *x,
                              TOKENEXTRA **t, int recon_yoffset,
                              int recon_uvoffset, int output_enabled,
                              int mb_col, int mb_row);

static void encode_superblock(VP9_COMP *cpi, MACROBLOCK *x,
                              TOKENEXTRA **t, int recon_yoffset,
                              int recon_uvoffset, int mb_col, int mb_row);

static void adjust_act_zbin(VP9_COMP *cpi, MACROBLOCK *x);

#ifdef MODE_STATS
unsigned int inter_y_modes[MB_MODE_COUNT];
unsigned int inter_uv_modes[VP9_UV_MODES];
unsigned int inter_b_modes[B_MODE_COUNT];
unsigned int y_modes[VP9_YMODES];
unsigned int i8x8_modes[VP9_I8X8_MODES];
unsigned int uv_modes[VP9_UV_MODES];
unsigned int uv_modes_y[VP9_YMODES][VP9_UV_MODES];
unsigned int b_modes[B_MODE_COUNT];
#endif


/* activity_avg must be positive, or flat regions could get a zero weight
 *  (infinite lambda), which confounds analysis.
 * This also avoids the need for divide by zero checks in
 *  vp9_activity_masking().
 */
#define VP9_ACTIVITY_AVG_MIN (64)

/* This is used as a reference when computing the source variance for the
 *  purposes of activity masking.
 * Eventually this should be replaced by custom no-reference routines,
 *  which will be faster.
 */
static const uint8_t VP9_VAR_OFFS[16] = {
  128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128
};


// Original activity measure from Tim T's code.
static unsigned int tt_activity_measure(VP9_COMP *cpi, MACROBLOCK *x) {
  unsigned int act;
  unsigned int sse;
  /* TODO: This could also be done over smaller areas (8x8), but that would
   *  require extensive changes elsewhere, as lambda is assumed to be fixed
   *  over an entire MB in most of the code.
   * Another option is to compute four 8x8 variances, and pick a single
   *  lambda using a non-linear combination (e.g., the smallest, or second
   *  smallest, etc.).
   */
  act = vp9_variance16x16(x->src.y_buffer, x->src.y_stride, VP9_VAR_OFFS, 0,
                          &sse);
  act = act << 4;

  /* If the region is flat, lower the activity some more. */
  if (act < 8 << 12)
    act = act < 5 << 12 ? act : 5 << 12;

  return act;
}

// Stub for alternative experimental activity measures.
static unsigned int alt_activity_measure(VP9_COMP *cpi,
                                         MACROBLOCK *x, int use_dc_pred) {
  return vp9_encode_intra(cpi, x, use_dc_pred);
}


// Measure the activity of the current macroblock
// What we measure here is TBD so abstracted to this function
#define ALT_ACT_MEASURE 1
static unsigned int mb_activity_measure(VP9_COMP *cpi, MACROBLOCK *x,
                                        int mb_row, int mb_col) {
  unsigned int mb_activity;

  if (ALT_ACT_MEASURE) {
    int use_dc_pred = (mb_col || mb_row) && (!mb_col || !mb_row);

    // Or use and alternative.
    mb_activity = alt_activity_measure(cpi, x, use_dc_pred);
  } else {
    // Original activity measure from Tim T's code.
    mb_activity = tt_activity_measure(cpi, x);
  }

  if (mb_activity < VP9_ACTIVITY_AVG_MIN)
    mb_activity = VP9_ACTIVITY_AVG_MIN;

  return mb_activity;
}

// Calculate an "average" mb activity value for the frame
#define ACT_MEDIAN 0
static void calc_av_activity(VP9_COMP *cpi, int64_t activity_sum) {
#if ACT_MEDIAN
  // Find median: Simple n^2 algorithm for experimentation
  {
    unsigned int median;
    unsigned int i, j;
    unsigned int *sortlist;
    unsigned int tmp;

    // Create a list to sort to
    CHECK_MEM_ERROR(sortlist,
    vpx_calloc(sizeof(unsigned int),
    cpi->common.MBs));

    // Copy map to sort list
    vpx_memcpy(sortlist, cpi->mb_activity_map,
    sizeof(unsigned int) * cpi->common.MBs);


    // Ripple each value down to its correct position
    for (i = 1; i < cpi->common.MBs; i ++) {
      for (j = i; j > 0; j --) {
        if (sortlist[j] < sortlist[j - 1]) {
          // Swap values
          tmp = sortlist[j - 1];
          sortlist[j - 1] = sortlist[j];
          sortlist[j] = tmp;
        } else
          break;
      }
    }

    // Even number MBs so estimate median as mean of two either side.
    median = (1 + sortlist[cpi->common.MBs >> 1] +
              sortlist[(cpi->common.MBs >> 1) + 1]) >> 1;

    cpi->activity_avg = median;

    vpx_free(sortlist);
  }
#else
  // Simple mean for now
  cpi->activity_avg = (unsigned int)(activity_sum / cpi->common.MBs);
#endif

  if (cpi->activity_avg < VP9_ACTIVITY_AVG_MIN)
    cpi->activity_avg = VP9_ACTIVITY_AVG_MIN;

  // Experimental code: return fixed value normalized for several clips
  if (ALT_ACT_MEASURE)
    cpi->activity_avg = 100000;
}

#define USE_ACT_INDEX   0
#define OUTPUT_NORM_ACT_STATS   0

#if USE_ACT_INDEX
// Calculate and activity index for each mb
static void calc_activity_index(VP9_COMP *cpi, MACROBLOCK *x) {
  VP9_COMMON *const cm = &cpi->common;
  int mb_row, mb_col;

  int64_t act;
  int64_t a;
  int64_t b;

#if OUTPUT_NORM_ACT_STATS
  FILE *f = fopen("norm_act.stt", "a");
  fprintf(f, "\n%12d\n", cpi->activity_avg);
#endif

  // Reset pointers to start of activity map
  x->mb_activity_ptr = cpi->mb_activity_map;

  // Calculate normalized mb activity number.
  for (mb_row = 0; mb_row < cm->mb_rows; mb_row++) {
    // for each macroblock col in image
    for (mb_col = 0; mb_col < cm->mb_cols; mb_col++) {
      // Read activity from the map
      act = *(x->mb_activity_ptr);

      // Calculate a normalized activity number
      a = act + 4 * cpi->activity_avg;
      b = 4 * act + cpi->activity_avg;

      if (b >= a)
        *(x->activity_ptr) = (int)((b + (a >> 1)) / a) - 1;
      else
        *(x->activity_ptr) = 1 - (int)((a + (b >> 1)) / b);

#if OUTPUT_NORM_ACT_STATS
      fprintf(f, " %6d", *(x->mb_activity_ptr));
#endif
      // Increment activity map pointers
      x->mb_activity_ptr++;
    }

#if OUTPUT_NORM_ACT_STATS
    fprintf(f, "\n");
#endif

  }

#if OUTPUT_NORM_ACT_STATS
  fclose(f);
#endif

}
#endif

// Loop through all MBs. Note activity of each, average activity and
// calculate a normalized activity for each
static void build_activity_map(VP9_COMP *cpi) {
  MACROBLOCK *const x = &cpi->mb;
  MACROBLOCKD *xd = &x->e_mbd;
  VP9_COMMON *const cm = &cpi->common;

#if ALT_ACT_MEASURE
  YV12_BUFFER_CONFIG *new_yv12 = &cm->yv12_fb[cm->new_fb_idx];
  int recon_yoffset;
  int recon_y_stride = new_yv12->y_stride;
#endif

  int mb_row, mb_col;
  unsigned int mb_activity;
  int64_t activity_sum = 0;

  // for each macroblock row in image
  for (mb_row = 0; mb_row < cm->mb_rows; mb_row++) {
#if ALT_ACT_MEASURE
    // reset above block coeffs
    xd->up_available = (mb_row != 0);
    recon_yoffset = (mb_row * recon_y_stride * 16);
#endif
    // for each macroblock col in image
    for (mb_col = 0; mb_col < cm->mb_cols; mb_col++) {
#if ALT_ACT_MEASURE
      xd->dst.y_buffer = new_yv12->y_buffer + recon_yoffset;
      xd->left_available = (mb_col != 0);
      recon_yoffset += 16;
#endif
#if !CONFIG_SUPERBLOCKS
      // Copy current mb to a buffer
      vp9_copy_mem16x16(x->src.y_buffer, x->src.y_stride, x->thismb, 16);
#endif

      // measure activity
      mb_activity = mb_activity_measure(cpi, x, mb_row, mb_col);

      // Keep frame sum
      activity_sum += mb_activity;

      // Store MB level activity details.
      *x->mb_activity_ptr = mb_activity;

      // Increment activity map pointer
      x->mb_activity_ptr++;

      // adjust to the next column of source macroblocks
      x->src.y_buffer += 16;
    }


    // adjust to the next row of mbs
    x->src.y_buffer += 16 * x->src.y_stride - 16 * cm->mb_cols;

#if ALT_ACT_MEASURE
    // extend the recon for intra prediction
    vp9_extend_mb_row(new_yv12, xd->dst.y_buffer + 16,
                      xd->dst.u_buffer + 8, xd->dst.v_buffer + 8);
#endif

  }

  // Calculate an "average" MB activity
  calc_av_activity(cpi, activity_sum);

#if USE_ACT_INDEX
  // Calculate an activity index number of each mb
  calc_activity_index(cpi, x);
#endif

}

// Macroblock activity masking
void vp9_activity_masking(VP9_COMP *cpi, MACROBLOCK *x) {
#if USE_ACT_INDEX
  x->rdmult += *(x->mb_activity_ptr) * (x->rdmult >> 2);
  x->errorperbit = x->rdmult * 100 / (110 * x->rddiv);
  x->errorperbit += (x->errorperbit == 0);
#else
  int64_t a;
  int64_t b;
  int64_t act = *(x->mb_activity_ptr);

  // Apply the masking to the RD multiplier.
  a = act + (2 * cpi->activity_avg);
  b = (2 * act) + cpi->activity_avg;

  x->rdmult = (unsigned int)(((int64_t)x->rdmult * b + (a >> 1)) / a);
  x->errorperbit = x->rdmult * 100 / (110 * x->rddiv);
  x->errorperbit += (x->errorperbit == 0);
#endif

  // Activity based Zbin adjustment
  adjust_act_zbin(cpi, x);
}

#if CONFIG_NEW_MVREF
static int vp9_cost_mv_ref_id(vp9_prob * ref_id_probs, int mv_ref_id) {
  int cost;

  // Encode the index for the MV reference.
  switch (mv_ref_id) {
    case 0:
      cost = vp9_cost_zero(ref_id_probs[0]);
      break;
    case 1:
      cost = vp9_cost_one(ref_id_probs[0]);
      cost += vp9_cost_zero(ref_id_probs[1]);
      break;
    case 2:
      cost = vp9_cost_one(ref_id_probs[0]);
      cost += vp9_cost_one(ref_id_probs[1]);
      cost += vp9_cost_zero(ref_id_probs[2]);
      break;
    case 3:
      cost = vp9_cost_one(ref_id_probs[0]);
      cost += vp9_cost_one(ref_id_probs[1]);
      cost += vp9_cost_one(ref_id_probs[2]);
      break;

      // TRAP.. This should not happen
    default:
      assert(0);
      break;
  }
  return cost;
}

// Estimate the cost of each coding the vector using each reference candidate
static unsigned int pick_best_mv_ref(MACROBLOCK *x,
                                     MV_REFERENCE_FRAME ref_frame,
                                     int_mv target_mv,
                                     int_mv * mv_ref_list,
                                     int_mv * best_ref) {
  int i;
  int best_index = 0;
  int cost, cost2;
  int zero_seen = (mv_ref_list[0].as_int) ? FALSE : TRUE;
  MACROBLOCKD *xd = &x->e_mbd;
  int max_mv = MV_MAX;

  cost = vp9_cost_mv_ref_id(xd->mb_mv_ref_probs[ref_frame], 0) +
         vp9_mv_bit_cost(&target_mv, &mv_ref_list[0], x->nmvjointcost,
                         x->mvcost, 96, xd->allow_high_precision_mv);

  for (i = 1; i < MAX_MV_REF_CANDIDATES; ++i) {
    // If we see a 0,0 reference vector for a second time we have reached
    // the end of the list of valid candidate vectors.
    if (!mv_ref_list[i].as_int) {
      if (zero_seen)
        break;
      else
        zero_seen = TRUE;
    }

    // Check for cases where the reference choice would give rise to an
    // uncodable/out of range residual for row or col.
    if ((abs(target_mv.as_mv.row - mv_ref_list[i].as_mv.row) > max_mv) ||
        (abs(target_mv.as_mv.col - mv_ref_list[i].as_mv.col) > max_mv)) {
      continue;
    }

    cost2 = vp9_cost_mv_ref_id(xd->mb_mv_ref_probs[ref_frame], i) +
            vp9_mv_bit_cost(&target_mv, &mv_ref_list[i], x->nmvjointcost,
                            x->mvcost, 96, xd->allow_high_precision_mv);

    if (cost2 < cost) {
      cost = cost2;
      best_index = i;
    }
  }
  best_ref->as_int = mv_ref_list[best_index].as_int;

  return best_index;
}
#endif

static void update_state(VP9_COMP *cpi, MACROBLOCK *x,
                         PICK_MODE_CONTEXT *ctx) {
  int i;
  MACROBLOCKD *xd = &x->e_mbd;
  MODE_INFO *mi = &ctx->mic;
  MB_MODE_INFO * mbmi = &xd->mode_info_context->mbmi;
  int mb_mode = mi->mbmi.mode;
  int mb_mode_index = ctx->best_mode_index;

#if CONFIG_DEBUG
  assert(mb_mode < MB_MODE_COUNT);
  assert(mb_mode_index < MAX_MODES);
  assert(mi->mbmi.ref_frame < MAX_REF_FRAMES);
#endif

  // Restore the coding context of the MB to that that was in place
  // when the mode was picked for it
  vpx_memcpy(xd->mode_info_context, mi, sizeof(MODE_INFO));
#if CONFIG_SUPERBLOCKS
  if (mi->mbmi.encoded_as_sb) {
    const int mis = cpi->common.mode_info_stride;
    if (xd->mb_to_right_edge >= 0)
      vpx_memcpy(xd->mode_info_context + 1, mi, sizeof(MODE_INFO));
    if (xd->mb_to_bottom_edge >= 0) {
      vpx_memcpy(xd->mode_info_context + mis, mi, sizeof(MODE_INFO));
      if (xd->mb_to_right_edge >= 0)
        vpx_memcpy(xd->mode_info_context + mis + 1, mi, sizeof(MODE_INFO));
    }
#if CONFIG_TX32X32 && CONFIG_SUPERBLOCKS
  } else {
    ctx->txfm_rd_diff[ALLOW_32X32] = ctx->txfm_rd_diff[ALLOW_16X16];
#endif
  }
#endif

  if (mb_mode == B_PRED) {
    for (i = 0; i < 16; i++) {
      xd->block[i].bmi.as_mode = xd->mode_info_context->bmi[i].as_mode;
      assert(xd->block[i].bmi.as_mode.first < B_MODE_COUNT);
    }
  } else if (mb_mode == I8X8_PRED) {
    for (i = 0; i < 16; i++) {
      xd->block[i].bmi = xd->mode_info_context->bmi[i];
    }
  } else if (mb_mode == SPLITMV) {
    vpx_memcpy(x->partition_info, &ctx->partition_info,
               sizeof(PARTITION_INFO));

    mbmi->mv[0].as_int = x->partition_info->bmi[15].mv.as_int;
    mbmi->mv[1].as_int = x->partition_info->bmi[15].second_mv.as_int;
  }

  {
    int segment_id = mbmi->segment_id;
    if (!vp9_segfeature_active(xd, segment_id, SEG_LVL_EOB) ||
        vp9_get_segdata(xd, segment_id, SEG_LVL_EOB)) {
      for (i = 0; i < NB_TXFM_MODES; i++) {
        cpi->rd_tx_select_diff[i] += ctx->txfm_rd_diff[i];
      }
    }
  }

  if (cpi->common.frame_type == KEY_FRAME) {
    // Restore the coding modes to that held in the coding context
    // if (mb_mode == B_PRED)
    //    for (i = 0; i < 16; i++)
    //    {
    //        xd->block[i].bmi.as_mode =
    //                          xd->mode_info_context->bmi[i].as_mode;
    //        assert(xd->mode_info_context->bmi[i].as_mode < MB_MODE_COUNT);
    //    }
#if CONFIG_INTERNAL_STATS
    static const int kf_mode_index[] = {
      THR_DC /*DC_PRED*/,
      THR_V_PRED /*V_PRED*/,
      THR_H_PRED /*H_PRED*/,
      THR_D45_PRED /*D45_PRED*/,
      THR_D135_PRED /*D135_PRED*/,
      THR_D117_PRED /*D117_PRED*/,
      THR_D153_PRED /*D153_PRED*/,
      THR_D27_PRED /*D27_PRED*/,
      THR_D63_PRED /*D63_PRED*/,
      THR_TM /*TM_PRED*/,
      THR_I8X8_PRED /*I8X8_PRED*/,
      THR_B_PRED /*B_PRED*/,
    };
    cpi->mode_chosen_counts[kf_mode_index[mb_mode]]++;
#endif
  } else {
    /*
            // Reduce the activation RD thresholds for the best choice mode
            if ((cpi->rd_baseline_thresh[mb_mode_index] > 0) &&
                (cpi->rd_baseline_thresh[mb_mode_index] < (INT_MAX >> 2)))
            {
                int best_adjustment = (cpi->rd_thresh_mult[mb_mode_index] >> 2);

                cpi->rd_thresh_mult[mb_mode_index] =
                        (cpi->rd_thresh_mult[mb_mode_index]
                         >= (MIN_THRESHMULT + best_adjustment)) ?
                                cpi->rd_thresh_mult[mb_mode_index] - best_adjustment :
                                MIN_THRESHMULT;
                cpi->rd_threshes[mb_mode_index] =
                        (cpi->rd_baseline_thresh[mb_mode_index] >> 7)
                        * cpi->rd_thresh_mult[mb_mode_index];

            }
    */
    // Note how often each mode chosen as best
    cpi->mode_chosen_counts[mb_mode_index]++;
    if (mbmi->mode == SPLITMV || mbmi->mode == NEWMV) {
      int_mv best_mv, best_second_mv;
      MV_REFERENCE_FRAME rf = mbmi->ref_frame;
#if CONFIG_NEW_MVREF
      unsigned int best_index;
      MV_REFERENCE_FRAME sec_ref_frame = mbmi->second_ref_frame;
#endif
      best_mv.as_int = ctx->best_ref_mv.as_int;
      best_second_mv.as_int = ctx->second_best_ref_mv.as_int;
      if (mbmi->mode == NEWMV) {
        best_mv.as_int = mbmi->ref_mvs[rf][0].as_int;
        best_second_mv.as_int = mbmi->ref_mvs[mbmi->second_ref_frame][0].as_int;
#if CONFIG_NEW_MVREF
        best_index = pick_best_mv_ref(x, rf, mbmi->mv[0],
                                      mbmi->ref_mvs[rf], &best_mv);
        mbmi->best_index = best_index;
        ++cpi->mb_mv_ref_count[rf][best_index];

        if (mbmi->second_ref_frame > 0) {
          unsigned int best_index;
          best_index =
              pick_best_mv_ref(x, sec_ref_frame, mbmi->mv[1],
                               mbmi->ref_mvs[sec_ref_frame],
                               &best_second_mv);
          mbmi->best_second_index = best_index;
          ++cpi->mb_mv_ref_count[sec_ref_frame][best_index];
        }
#endif
      }
      mbmi->best_mv.as_int = best_mv.as_int;
      mbmi->best_second_mv.as_int = best_second_mv.as_int;
      vp9_update_nmv_count(cpi, x, &best_mv, &best_second_mv);
    }
#if CONFIG_COMP_INTERINTRA_PRED
    if (mbmi->mode >= NEARESTMV && mbmi->mode < SPLITMV &&
        mbmi->second_ref_frame <= INTRA_FRAME) {
      if (mbmi->second_ref_frame == INTRA_FRAME) {
        ++cpi->interintra_count[1];
        ++cpi->ymode_count[mbmi->interintra_mode];
#if SEPARATE_INTERINTRA_UV
        ++cpi->y_uv_mode_count[mbmi->interintra_mode][mbmi->interintra_uv_mode];
#endif
      } else {
        ++cpi->interintra_count[0];
      }
    }
#endif
    if (cpi->common.mcomp_filter_type == SWITCHABLE &&
        mbmi->mode >= NEARESTMV &&
        mbmi->mode <= SPLITMV) {
      ++cpi->switchable_interp_count
          [vp9_get_pred_context(&cpi->common, xd, PRED_SWITCHABLE_INTERP)]
          [vp9_switchable_interp_map[mbmi->interp_filter]];
    }

    cpi->prediction_error += ctx->distortion;
    cpi->intra_error += ctx->intra_error;

    cpi->rd_comp_pred_diff[SINGLE_PREDICTION_ONLY] += ctx->single_pred_diff;
    cpi->rd_comp_pred_diff[COMP_PREDICTION_ONLY]   += ctx->comp_pred_diff;
    cpi->rd_comp_pred_diff[HYBRID_PREDICTION]      += ctx->hybrid_pred_diff;
  }
}

static void pick_mb_modes(VP9_COMP *cpi,
                          VP9_COMMON *cm,
                          int mb_row,
                          int mb_col,
                          MACROBLOCK  *x,
                          MACROBLOCKD *xd,
                          TOKENEXTRA **tp,
                          int *totalrate,
                          int *totaldist) {
  int i;
  int map_index;
  int recon_yoffset, recon_uvoffset;
  int ref_fb_idx = cm->lst_fb_idx;
  int dst_fb_idx = cm->new_fb_idx;
  int recon_y_stride = cm->yv12_fb[ref_fb_idx].y_stride;
  int recon_uv_stride = cm->yv12_fb[ref_fb_idx].uv_stride;
  ENTROPY_CONTEXT_PLANES left_context[2];
  ENTROPY_CONTEXT_PLANES above_context[2];
  ENTROPY_CONTEXT_PLANES *initial_above_context_ptr = cm->above_context
                                                      + mb_col;

  // Offsets to move pointers from MB to MB within a SB in raster order
  int row_delta[4] = { 0, +1,  0, -1};
  int col_delta[4] = { +1, -1, +1, +1};

  /* Function should not modify L & A contexts; save and restore on exit */
  vpx_memcpy(left_context,
             cm->left_context,
             sizeof(left_context));
  vpx_memcpy(above_context,
             initial_above_context_ptr,
             sizeof(above_context));

  /* Encode MBs in raster order within the SB */
  for (i = 0; i < 4; i++) {
    int dy = row_delta[i];
    int dx = col_delta[i];
    int offset_unextended = dy * cm->mb_cols + dx;
    int offset_extended   = dy * xd->mode_info_stride + dx;
    MB_MODE_INFO * mbmi = &xd->mode_info_context->mbmi;

    // TODO Many of the index items here can be computed more efficiently!

    if ((mb_row >= cm->mb_rows) || (mb_col >= cm->mb_cols)) {
      // MB lies outside frame, move on
      mb_row += dy;
      mb_col += dx;

      // Update pointers
      x->src.y_buffer += 16 * (dx + dy * x->src.y_stride);
      x->src.u_buffer += 8  * (dx + dy * x->src.uv_stride);
      x->src.v_buffer += 8  * (dx + dy * x->src.uv_stride);

      x->gf_active_ptr += offset_unextended;
      x->partition_info += offset_extended;
      xd->mode_info_context += offset_extended;
      xd->prev_mode_info_context += offset_extended;
#if CONFIG_DEBUG
      assert((xd->prev_mode_info_context - cpi->common.prev_mip) ==
             (xd->mode_info_context - cpi->common.mip));
#endif
      continue;
    }

    // Index of the MB in the SB 0..3
    xd->mb_index = i;

    map_index = (mb_row * cpi->common.mb_cols) + mb_col;
    x->mb_activity_ptr = &cpi->mb_activity_map[map_index];

    // set above context pointer
    xd->above_context = cm->above_context + mb_col;

    // Restore the appropriate left context depending on which
    // row in the SB the MB is situated
    xd->left_context = cm->left_context + (i >> 1);

    // Set up distance of MB to edge of frame in 1/8th pel units
    xd->mb_to_top_edge    = -((mb_row * 16) << 3);
    xd->mb_to_left_edge   = -((mb_col * 16) << 3);
    xd->mb_to_bottom_edge = ((cm->mb_rows - 1 - mb_row) * 16) << 3;
    xd->mb_to_right_edge  = ((cm->mb_cols - 1 - mb_col) * 16) << 3;

    // Set up limit values for MV components to prevent them from
    // extending beyond the UMV borders assuming 16x16 block size
    x->mv_row_min = -((mb_row * 16) + VP9BORDERINPIXELS - VP9_INTERP_EXTEND);
    x->mv_col_min = -((mb_col * 16) + VP9BORDERINPIXELS - VP9_INTERP_EXTEND);
    x->mv_row_max = ((cm->mb_rows - mb_row) * 16 +
                     (VP9BORDERINPIXELS - 16 - VP9_INTERP_EXTEND));
    x->mv_col_max = ((cm->mb_cols - mb_col) * 16 +
                     (VP9BORDERINPIXELS - 16 - VP9_INTERP_EXTEND));

    xd->up_available   = (mb_row != 0);
    xd->left_available = (mb_col != 0);

    recon_yoffset  = (mb_row * recon_y_stride * 16) + (mb_col * 16);
    recon_uvoffset = (mb_row * recon_uv_stride * 8) + (mb_col *  8);

    xd->dst.y_buffer = cm->yv12_fb[dst_fb_idx].y_buffer + recon_yoffset;
    xd->dst.u_buffer = cm->yv12_fb[dst_fb_idx].u_buffer + recon_uvoffset;
    xd->dst.v_buffer = cm->yv12_fb[dst_fb_idx].v_buffer + recon_uvoffset;

#if !CONFIG_SUPERBLOCKS
    // Copy current MB to a work buffer
    vp9_copy_mem16x16(x->src.y_buffer, x->src.y_stride, x->thismb, 16);
#endif

    x->rddiv = cpi->RDDIV;
    x->rdmult = cpi->RDMULT;

    if (cpi->oxcf.tuning == VP8_TUNE_SSIM)
      vp9_activity_masking(cpi, x);

    // Is segmentation enabled
    if (xd->segmentation_enabled) {
      // Code to set segment id in xd->mbmi.segment_id
      if (xd->update_mb_segmentation_map)
        mbmi->segment_id = cpi->segmentation_map[map_index];
      else
        mbmi->segment_id = cm->last_frame_seg_map[map_index];
      if (mbmi->segment_id > 3)
        mbmi->segment_id = 0;

      vp9_mb_init_quantizer(cpi, x);
    } else
      // Set to Segment 0 by default
      mbmi->segment_id = 0;

    x->active_ptr = cpi->active_map + map_index;

#if CONFIG_SUPERBLOCKS
    xd->mode_info_context->mbmi.encoded_as_sb = 0;
#endif

    cpi->update_context = 0;    // TODO Do we need this now??

    vp9_intra_prediction_down_copy(xd);

#ifdef ENC_DEBUG
      enc_debug = (cpi->common.current_video_frame == 46 &&
                   mb_row == 5 && mb_col == 2);
#endif
    // Find best coding mode & reconstruct the MB so it is available
    // as a predictor for MBs that follow in the SB
    if (cm->frame_type == KEY_FRAME) {
      int r, d;
#ifdef ENC_DEBUG
      if (enc_debug)
        printf("intra pick_mb_modes %d %d\n", mb_row, mb_col);
#endif
      vp9_rd_pick_intra_mode(cpi, x, &r, &d);
      *totalrate += r;
      *totaldist += d;

      // Dummy encode, do not do the tokenization
      encode_macroblock(cpi, x, tp,
                        recon_yoffset, recon_uvoffset, 0, mb_col, mb_row);
      // Note the encoder may have changed the segment_id

      // Save the coding context
      vpx_memcpy(&x->mb_context[i].mic, xd->mode_info_context,
                 sizeof(MODE_INFO));
    } else {
      int seg_id, r, d;

      if (xd->segmentation_enabled && cpi->seg0_cnt > 0 &&
          !vp9_segfeature_active(xd, 0, SEG_LVL_REF_FRAME) &&
          vp9_segfeature_active(xd, 1, SEG_LVL_REF_FRAME) &&
          vp9_check_segref(xd, 1, INTRA_FRAME)  +
          vp9_check_segref(xd, 1, LAST_FRAME)   +
          vp9_check_segref(xd, 1, GOLDEN_FRAME) +
          vp9_check_segref(xd, 1, ALTREF_FRAME) == 1) {
        cpi->seg0_progress = (cpi->seg0_idx << 16) / cpi->seg0_cnt;
      } else {
        cpi->seg0_progress = (((mb_col & ~1) * 2 + (mb_row & ~1) * cm->mb_cols + i) << 16) / cm->MBs;
      }

#ifdef ENC_DEBUG
      if (enc_debug)
        printf("inter pick_mb_modes %d %d\n", mb_row, mb_col);
#endif
      vp9_pick_mode_inter_macroblock(cpi, x, recon_yoffset,
                                     recon_uvoffset, &r, &d);
      *totalrate += r;
      *totaldist += d;

      // Dummy encode, do not do the tokenization
      encode_macroblock(cpi, x, tp,
                        recon_yoffset, recon_uvoffset, 0, mb_col, mb_row);

      seg_id = mbmi->segment_id;
      if (cpi->mb.e_mbd.segmentation_enabled && seg_id == 0) {
        cpi->seg0_idx++;
      }
      if (!xd->segmentation_enabled ||
          !vp9_segfeature_active(xd, seg_id, SEG_LVL_REF_FRAME) ||
          vp9_check_segref(xd, seg_id, INTRA_FRAME)  +
          vp9_check_segref(xd, seg_id, LAST_FRAME)   +
          vp9_check_segref(xd, seg_id, GOLDEN_FRAME) +
          vp9_check_segref(xd, seg_id, ALTREF_FRAME) > 1) {
        // Get the prediction context and status
        int pred_flag = vp9_get_pred_flag(xd, PRED_REF);
        int pred_context = vp9_get_pred_context(cm, xd, PRED_REF);

        // Count prediction success
        cpi->ref_pred_count[pred_context][pred_flag]++;
      }
    }

    // Next MB
    mb_row += dy;
    mb_col += dx;

    x->src.y_buffer += 16 * (dx + dy * x->src.y_stride);
    x->src.u_buffer += 8  * (dx + dy * x->src.uv_stride);
    x->src.v_buffer += 8  * (dx + dy * x->src.uv_stride);

    x->gf_active_ptr += offset_unextended;
    x->partition_info += offset_extended;
    xd->mode_info_context += offset_extended;
    xd->prev_mode_info_context += offset_extended;

#if CONFIG_DEBUG
    assert((xd->prev_mode_info_context - cpi->common.prev_mip) ==
           (xd->mode_info_context - cpi->common.mip));
#endif
  }

  /* Restore L & A coding context to those in place on entry */
  vpx_memcpy(cm->left_context,
             left_context,
             sizeof(left_context));
  vpx_memcpy(initial_above_context_ptr,
             above_context,
             sizeof(above_context));
}

#if CONFIG_SUPERBLOCKS
static void pick_sb_modes (VP9_COMP *cpi,
                           VP9_COMMON *cm,
                           int mb_row,
                           int mb_col,
                           MACROBLOCK  *x,
                           MACROBLOCKD *xd,
                           TOKENEXTRA **tp,
                           int *totalrate,
                           int *totaldist)
{
  int map_index;
  int recon_yoffset, recon_uvoffset;
  int ref_fb_idx = cm->lst_fb_idx;
  int dst_fb_idx = cm->new_fb_idx;
  int recon_y_stride = cm->yv12_fb[ref_fb_idx].y_stride;
  int recon_uv_stride = cm->yv12_fb[ref_fb_idx].uv_stride;
  ENTROPY_CONTEXT_PLANES left_context[2];
  ENTROPY_CONTEXT_PLANES above_context[2];
  ENTROPY_CONTEXT_PLANES *initial_above_context_ptr = cm->above_context
    + mb_col;

  /* Function should not modify L & A contexts; save and restore on exit */
  vpx_memcpy (left_context,
              cm->left_context,
              sizeof(left_context));
  vpx_memcpy (above_context,
              initial_above_context_ptr,
              sizeof(above_context));

  map_index = (mb_row * cpi->common.mb_cols) + mb_col;
  x->mb_activity_ptr = &cpi->mb_activity_map[map_index];

  /* set above context pointer */
  xd->above_context = cm->above_context + mb_col;

  /* Restore the appropriate left context depending on which
   * row in the SB the MB is situated */
  xd->left_context = cm->left_context;

  // Set up distance of MB to edge of frame in 1/8th pel units
  xd->mb_to_top_edge    = -((mb_row * 16) << 3);
  xd->mb_to_left_edge   = -((mb_col * 16) << 3);
  xd->mb_to_bottom_edge = ((cm->mb_rows - 2 - mb_row) * 16) << 3;
  xd->mb_to_right_edge  = ((cm->mb_cols - 2 - mb_col) * 16) << 3;

  /* Set up limit values for MV components to prevent them from
   * extending beyond the UMV borders assuming 16x16 block size */
  x->mv_row_min = -((mb_row * 16) + VP9BORDERINPIXELS - VP9_INTERP_EXTEND);
  x->mv_col_min = -((mb_col * 16) + VP9BORDERINPIXELS - VP9_INTERP_EXTEND);
  x->mv_row_max = ((cm->mb_rows - mb_row) * 16 +
                   (VP9BORDERINPIXELS - 32 - VP9_INTERP_EXTEND));
  x->mv_col_max = ((cm->mb_cols - mb_col) * 16 +
                   (VP9BORDERINPIXELS - 32 - VP9_INTERP_EXTEND));

  xd->up_available   = (mb_row != 0);
  xd->left_available = (mb_col != 0);

  recon_yoffset  = (mb_row * recon_y_stride * 16) + (mb_col * 16);
  recon_uvoffset = (mb_row * recon_uv_stride * 8) + (mb_col *  8);

  xd->dst.y_buffer = cm->yv12_fb[dst_fb_idx].y_buffer + recon_yoffset;
  xd->dst.u_buffer = cm->yv12_fb[dst_fb_idx].u_buffer + recon_uvoffset;
  xd->dst.v_buffer = cm->yv12_fb[dst_fb_idx].v_buffer + recon_uvoffset;
#if 0 // FIXME
  /* Copy current MB to a work buffer */
  vp9_copy_mem16x16(x->src.y_buffer, x->src.y_stride, x->thismb, 16);
#endif
  x->rddiv = cpi->RDDIV;
  x->rdmult = cpi->RDMULT;
  if(cpi->oxcf.tuning == VP8_TUNE_SSIM)
    vp9_activity_masking(cpi, x);
  /* Is segmentation enabled */
  if (xd->segmentation_enabled)
  {
    /* Code to set segment id in xd->mbmi.segment_id */
    if (xd->update_mb_segmentation_map)
      xd->mode_info_context->mbmi.segment_id =
            cpi->segmentation_map[map_index] &&
            cpi->segmentation_map[map_index + 1] &&
            cpi->segmentation_map[map_index + cm->mb_cols] &&
            cpi->segmentation_map[map_index + cm->mb_cols + 1];
    else
      xd->mode_info_context->mbmi.segment_id =
            cm->last_frame_seg_map[map_index] &&
            cm->last_frame_seg_map[map_index + 1] &&
            cm->last_frame_seg_map[map_index + cm->mb_cols] &&
            cm->last_frame_seg_map[map_index + cm->mb_cols + 1];
    if (xd->mode_info_context->mbmi.segment_id > 3)
      xd->mode_info_context->mbmi.segment_id = 0;

    vp9_mb_init_quantizer(cpi, x);
  }
  else
    /* Set to Segment 0 by default */
    xd->mode_info_context->mbmi.segment_id = 0;

  x->active_ptr = cpi->active_map + map_index;

  cpi->update_context = 0;    // TODO Do we need this now??

  /* Find best coding mode & reconstruct the MB so it is available
   * as a predictor for MBs that follow in the SB */
  if (cm->frame_type == KEY_FRAME)
  {
    vp9_rd_pick_intra_mode_sb(cpi, x,
                              totalrate,
                              totaldist);

    /* Save the coding context */
    vpx_memcpy(&x->sb_context[0].mic, xd->mode_info_context,
               sizeof(MODE_INFO));
  } else {
    if (xd->segmentation_enabled && cpi->seg0_cnt > 0 &&
        !vp9_segfeature_active(xd, 0, SEG_LVL_REF_FRAME) &&
        vp9_segfeature_active(xd, 1, SEG_LVL_REF_FRAME) &&
        vp9_check_segref(xd, 1, INTRA_FRAME)  +
        vp9_check_segref(xd, 1, LAST_FRAME)   +
        vp9_check_segref(xd, 1, GOLDEN_FRAME) +
        vp9_check_segref(xd, 1, ALTREF_FRAME) == 1) {
      cpi->seg0_progress = (cpi->seg0_idx << 16) / cpi->seg0_cnt;
    } else {
      cpi->seg0_progress =
        (((mb_col & ~1) * 2 + (mb_row & ~1) * cm->mb_cols) << 16) / cm->MBs;
    }

    vp9_rd_pick_inter_mode_sb(cpi, x,
                              recon_yoffset,
                              recon_uvoffset,
                              totalrate,
                              totaldist);
  }

  /* Restore L & A coding context to those in place on entry */
  vpx_memcpy (cm->left_context,
              left_context,
              sizeof(left_context));
  vpx_memcpy (initial_above_context_ptr,
              above_context,
              sizeof(above_context));
}
#endif

static void encode_sb(VP9_COMP *cpi,
                      VP9_COMMON *cm,
                      int mbrow,
                      int mbcol,
                      MACROBLOCK  *x,
                      MACROBLOCKD *xd,
                      TOKENEXTRA **tp) {
  int i;
  int map_index;
  int mb_row, mb_col;
  int recon_yoffset, recon_uvoffset;
  int ref_fb_idx = cm->lst_fb_idx;
  int dst_fb_idx = cm->new_fb_idx;
  int recon_y_stride = cm->yv12_fb[ref_fb_idx].y_stride;
  int recon_uv_stride = cm->yv12_fb[ref_fb_idx].uv_stride;